var x2;

var x3;

var y1;

var y2;

var y3;

​

function setup() {

  createCanvas(600, 600);

}

​

function draw() {

  background(220);

  strokeWeight(2);

  fill(0);

  ellipse(x1, y1, 10);

  ellipse(x2, y2, 10);

  ellipse(x3, y3, 10);

  line(x1,y1, x2,y2);

  line(x2,y2,x3,y3);

  line(x3,y3,x1,y1);

  var ma = (y2-y1)/(x2-x1);

  var mb = (y3-y2)/(x3-x2);

  let cx = (ma*mb*(y1-y3) + mb*(x1+x2) - ma*(x2+x3))/(2*(mb-ma));

  let cy = (-1/ma)*(cx-(x1+x2)/2) + (y1+y2)/2;

  var dx = x1-cx;

  var dy = y1-cy;

  var radius = sqrt(dx**2 + dy**2);

  noFill();

  ellipse(cx, cy, radius*2, radius*2);

}

​

function mousePressed() {

  x1 = random(width);

  x2 = random(width);

  x3 = random(width);

  y1 = random(height);

  y2 = random(height);

  y3 = random(height);

  return false;

}